The Vow, a full-bodied lunge for the heartstrings, has a humdinger of a premise, forcing its characters to face a question that most of us ask ourselves: If you could do the past five years over again, would you live them the same or take a mulligan?

A young married couple, Leo and Paige (Channing Tatum and Rachel McAdams), are rear-ended on a snowy Chicago night. He's all right, but she comes to with no memory of the past half-decade. These have been years of significant change. Asking who the president is, she's shocked to discover that it's Senator Obama — and, more shockingly, that she voted for him. Paige remembers being engaged to another man (Scott Speedman) in law school and preparing for a suburban life much like that of her parents (Sam Neill and Jessica Lange) in exclusive Lake Forest. Now she's married to a man she doesn't recognize, estranged from her posh upbringing, and working as a sculptor.

With no memories to ballast her to Leo and their life, Paige gravitates back toward the past that she'd jettisoned; Leo is pained, patient, and beseeching but privately appalled that the hip free spirit whom he married has regressed into a "sweater set–wearing, mojito-drinking sorority girl," now flirting with the ex-fiancé.

The Vow announces from the top that it is "inspired by true events," but though the film nods to mounting bills and professional stress surrounding the accident, anything resembling the actual pressures of social-economic reality are waved off as significant factors in Paige's decision between lives. No starving artists, Leo and Paige were living the bohemian-bourgeoisie ideal, with a dream loft and cool, promising careers — she pulling in corporate commissions, he running his own recording studio.

Capsulizing the complex differences between Paige's choices into easy-to-swallow forms — and highlighting the "right" choice for the viewer — The Vow makes the least of its concept, refusing to acknowledge that a love need not be perfect to merit holding on to (something the similarly themed Eternal Sunshine of the Spotless Mind understood). The Vow does, however, offer an unobstructed view of charismatic performers, playing people working earnestly at a rather impossible situation. Bullnecked Tatum is about as convincing a studio nerd as Steve Albini would be as an Abercrombie model, but his shy manner around his stranger of a wife is touching — throat-clearing line readings that break down to butting his head against the immovable object of her mental block. After Wedding Crashers and Midnight in Paris, McAdams might seem consigned to representing the horror of WASP aridity, but she brings a bright bemusement to her part that refines Paige's crude dilemma, as though, having lived two stereotyped identities, she's able to find the joke in both. Closes with the Cure's "Pictures of You," and a chorus of sniffling.